WTPS31 PGTW 062100 MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI// SUBJ/TROPICAL CYCLONE 23P (NIRAN) WARNING NR 024// RMKS/ 1. TROPICAL CYCLONE 23P (NIRAN) WARNING NR 024 01 ACTIVE TROPICAL CYCLONE IN SOUTHPAC MAX SUSTAINED WINDS BASED ON ONE-MINUTE AVERAGE WIND RADII VALID OVER OPEN WATER ONLY --- WARNING POSITION: 061800Z --- NEAR 26.7S 173.5E MOVEMENT PAST SIX HOURS - 125 DEGREES AT 43 KTS POSITION ACCURATE TO WITHIN 045 NM POSITION BASED ON CENTER LOCATED BY SATELLITE PRESENT WIND DISTRIBUTION: MAX SUSTAINED WINDS - 065 KT, GUSTS 080 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 064 KT WINDS - 030 NM NORTHEAST QUADRANT 020 NM SOUTHEAST QUADRANT 020 NM SOUTHWEST QUADRANT 030 NM NORTHWEST QUADRANT RADIUS OF 050 KT WINDS - 115 NM NORTHEAST QUADRANT 100 NM SOUTHEAST QUADRANT 075 NM SOUTHWEST QUADRANT 095 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 195 NM NORTHEAST QUADRANT 175 NM SOUTHEAST QUADRANT 135 NM SOUTHWEST QUADRANT 170 NM NORTHWEST QUADRANT REPEAT POSIT: 26.7S 173.5E --- FORECASTS: 12 HRS, VALID AT: 070600Z --- 29.3S 179.8E MAX SUSTAINED WINDS - 050 KT, GUSTS 065 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 050 KT WINDS - 040 NM NORTHEAST QUADRANT 030 NM SOUTHEAST QUADRANT 030 NM SOUTHWEST QUADRANT 040 NM NORTHWEST QUADRANT RADIUS OF 034 KT WINDS - 160 NM NORTHEAST QUADRANT 130 NM SOUTHEAST QUADRANT 110 NM SOUTHWEST QUADRANT 140 NM NORTHWEST QUADRANT VECTOR TO 24 HR POSIT: 110 DEG/ 27 KTS --- 24 HRS, VALID AT: 071800Z --- 31.0S 174.3W MAX SUSTAINED WINDS - 035 KT, GUSTS 045 KT WIND RADII VALID OVER OPEN WATER ONLY BECOMING SUBTROPICAL RADIUS OF 034 KT WINDS - 100 NM NORTHEAST QUADRANT 060 NM SOUTHEAST QUADRANT 090 NM SOUTHWEST QUADRANT 150 NM NORTHWEST QUADRANT VECTOR TO 36 HR POSIT: 105 DEG/ 20 KTS --- 36 HRS, VALID AT: 080600Z --- 31.8S 169.7W MAX SUSTAINED WINDS - 030 KT, GUSTS 040 KT WIND RADII VALID OVER OPEN WATER ONLY SUBTROPICAL --- REMARKS: 062100Z POSITION NEAR 27.3S 175.1E. 06MAR21. TROPICAL CYCLONE 23P (NIRAN), LOCATED APPROXIMATELY 489 NM SOUTHEAST OF NOUMEA, NEW CALEDONI, HAS TRACKED SOUTHEASTWARD AT 43 KNOTS OVER THE PAST SIX HOURS. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) SHOWS THE SYSTEM HAS BECOME MORE ELONGATED WITH FRONTAL CHARACTERISTICS AND HAS ACCELERATED RAPIDLY TO THE SOUTHEAST. ADDITIONALLY, COLD AIR STRATOCUMULUS CLOUDS CAN BE SEEN FEEDING TOWARD THE LOW LEVEL CIRCULATION HAS BECOME PARTIALLY EXPOSED. THE INITIAL POSITION WAS PLACED WITH FAIR CONFIDENCE USING THE 061814Z SSMIS 91GHZ IMAGE. THE INITIAL INTENSITY OF 65KTS IS BASED ON AN OVERALL ASSESSMENT OF THE ADVANCED DVORAK TECHNIQUE (ADT) WITH A CURRENT INTENSITY ESTIMATE OF T4.0/65KTS, WHICH IS HEDGED LOWER THAN PGTW T5.0/90KTS BOUND BY CONSTRAINTS. UPPER LEVEL ANALYSIS INDICATES ROBUST POLEWARD OUTFLOW THAT IS OFFSET BY VERY STRONG (40KTS+) VERTICAL WIND SHEAR AND SEA SURFACE TEMPERATURES (SSTS) WHICH HAVE LOWERED TO 24-25C. THE CYCLONE IS CONTINUALLY ACCELERATING SOUTHEAST ALONG THE SOUTHWEST PERIPHERY OF THE DEEP LAYERED SUBTROPICAL RIDGE TO THE EAST. HARSH UPPER LEVEL DYNAMICS AND SSTS DROPPING TO <24C, WILL LEAD TO RAPID WEAKENING TO 35KTS BY TAU 24. CONCURRENTLY, TC NIRAN IS ALREADY UNDERGOING A SUBTROPICAL TRANSITION AND WILL BECOME FULLY SUBTROPICAL BY TAU 36. NUMERICAL MODELS ARE IN FAIR AGREEMENT THROUGH TAU 24 WITH ONLY A 175NM SPREAD. AFTERWARDS, THE SOLUTIONS DIVERGE AS THE ALONG TRACK / CROSS TRACK SPREAD INCREASES PAST TAU 36. THERE IS MODERATE CONFIDENCE IN THE FIRST 24 HOURS OF THE FORECAST TRACK AND LOW CONFIDENCE THEREAFTER DUE TO THE INCREASING SPREAD IN MODEL SOLUTIONS. MAXIMUM SIGNIFICANT WAVE HEIGHT AT 061800Z IS 30 FEET. NEXT WARNINGS AT 070300Z, 070900Z, 071500Z AND 072100Z.// NNNN